Saint Louis Encephalitis Virus

The mosquito-borne illness Saint Louis encephalitis is similar to other viruses that mosquitos spread, such as West Nile virus, yellow fever virus and dengue fever virus. The primary species of mosquito that spreads St. Louis encephalitis (or SLEV) is the Culex species. These mosquitos are found primarily in the eastern and central United States, although some western rural states have reported cases of SLEV too. Saint Louis encephalitis dates back to the 1930s.

Saint Louis encephalitis is a virus carried by both mosquitos and birds. However, SLEV does not cause either type of animal to become ill. Instead, it only infects mammals, such as humans, when the infected mosquitos bite. The virus remains active by transmitting from mosquitos to birds and back to mosquitos. This back and forth activation of the virus often results in SLEV infections appearing more heavily in cycles.

Symptoms of St. Louis encephalitis may not show up in some people infected with the virus, meaning they may not even realize they have the illness. Others may develop a mild case of SLEV within 4 to 21 days of the initial infection from the mosquito bite. The mild form of the disease results in fever and headaches.

Serious cases of the illness include symptoms such as high fever, neck stiffness and persisting headaches. As the disease progresses, infected people may develop tremors, convulsions, stupor, disorientation and spastic paralysis. Infants and older adults run the risk of developing a more severe form of Saint Louis encephalitis, which can result in death.

There is no specific treatment or preventative vaccine available to deal with Saint Louis encephalitis. Those infected with the virus should seek help from medical professionals, who will apply supportive treatment as needed to deal with the symptoms.

The best way to avoid any chance of a Saint Louis encephalitis infection is through prevention. Wearing long clothing and using insect repellant helps reduce the chances of suffering a mosquito bite. Use of fogging products from MosquitoNix® also can reduce the number of mosquitos in your backyard or neighborhood, as well as ticks.